Liquid I, in one bottle.—Dissolve 36 parts of sodium fluoride in 500 parts of distilled water and add 7 parts of potassium sulphate.
Liquid II, in another bottle.—Dissolve zinc chloride, 14 parts, in 500 parts of distilled water, and add 65 parts of concentrated hydrochloric acid.
For use mix equal parts together and add a little dissolved India ink to render the writing more visible.
The mixing cannot, however, be conducted in a vessel. It is best to use a cube of paraffine which has been hollowed out.
Etching On Marble Or Ivory
Etching On Steel.
Liquids For Etching Steel.—
| I.— | Iodine | 2 parts |
|---|---|---|
| Potassium iodide | 5 parts | |
| Water | 40 parts | |
| II.— | Nitric acid | 60 parts |
| Water | 120 parts | |
| Alcohol | 200 parts | |
| Copper nitrate | 8 parts | |
| III.— | Glacial acetic acid | 4 parts |
| Nitric acid | 1 part | |
| Alcohol | 1 part |
IV.—Mix 1 ounce sulphate of copper, 1/4 ounce alum, 1/2 teaspoonful of salt (reduced to powder), with 1 gill of vinegar and 20 drops of nitric acid. This fluid can be used either for etching deeply or for frosting, according to the time it is allowed to act. The parts of the work which are not to be etched should be protected with beeswax or some similar substance.
V.—Nitric acid, 60 parts; water, 120 parts; alcohol, 200 parts; and copper nitrate, 8 parts. Keep in a glass-stoppered bottle. To use the fluid, cover the surface to be marked with a thin even coat of wax and mark the lines with a machinist’s scriber. Wrap clean cotton waste around the end of the scriber or a stick, and dip in the fluid, applying it to the marked surface. In a few minutes the wax may be scraped off, when fine lines will appear where the scriber marked the wax. The drippings from a lighted wax candle can be used for the {328} coating, and this may be evenly spread with a knife heated in the candle flame.